Arc extinguishing structure with venting passage and deflector means



March 2, 1965 c. L. JENCKS ETAL ARC sxwmcmsmuc STRUCTURE WITH VENTING PASSAGE AND DEFLECTOR MEANS Filed July 27, 1962 A f! F FIGJ F'IG.Z

INVENTORS CHARLES L. (/ENCKS, KE/TH W. KLEIN ATTORNEY.

United States Patent 71,936 ARC EX'IINGUISHING STRUCTURE WITH VENT- ING PASSAGE AND DEFLECTOR MEANS Charles L. Jencks, Avon, and KeithW. Klein, Simsbury, Conn., assignors 'to General Electric Company, a corporation of New York Filed July 27, 1962, Ser. No. 212,333 2 Claims. (Cl, 206 -144) The present invention relates to electric circuit interrupters and particularly to electric circuit interrupters including means for interrupting relatively high or short circuit currents.

Electric circuit interrupters of the type reierred to includemanually operable contact means having a nominal current carrying and interruptingrating of relatively low or intermediate value, such for example as 225 amperes. Such interrupters are also automatically operable to interrupt the current upon the occurrence of predetermined abnormal current conditions. Among such abnormal current conditions, are short circuit current conditions, having potential values of. 540,000 or more amperes. When currents of such short circuit magnitude are drawn between contacts operating in air, an electric arc is drawn Which must be cooled and 'extinguish ed or dc-ionized without damaging the internal operating parts of the circuit interrupter. The forces associated. with an arc of such value are. essentially explosive in nature, and the ionized arc gases tend to. expand rapidly in all direc-v tions. In some cases, such gases are likely to blow back into the circuit breaker mechanism, causing damage to the parts or danger of creating electrical breakdown between parts which are of different electricalpotential.

It as object of the present invention to provide an electric circuit interrupter of t-he type including contacts operating in air to draw an electric are which, shall include means for causing movement of the are through are cool ing means to a venting openingin the interrupter enclosure and to direct the arc gases outwardly of the enclosure and also toprevent backward fiow of such gases toward the interior or mechanism chamber of the interrupter.

In accordance with the invention in one form, an electric circuit interrupter is provided comprising an insulating enclosure and at least one pair of contacts operating inthe enclosure. Arc extinguishing means is provided adjacent the contacts comprising a stack of spaced metallic plates supported between a pair of opposed insulating side plate members. The ends of the side plates are spaced away from the adjacent end wall of the circuit breaker, leaving a vertical channel adjacent the arc chute assembly. An opening or vent is provided in the interrupter housing adjacent the top Wall thereof. Means is provided for preventing the arc gases from blowing back into the mechanism chamber of the interrupter, including an arc deflector plate adjacent the upper end of the arc passage for guiding the arc gasses out the vent opening and preventing them from blowing back into the circuit breaker mechanism chamber. Means is also provided for closing the bottom end of the arc vent passage comprising a bottom arc chute plate which is made extra thick and which projects beyond the main arc chute assembly to close off the vertical arc passage at the bottom thereof and also to provide a large heat-receiving body.

The invention Will be more fully understood from the following detailed description, and its scope will be pointed out in the appended claims.

In the drawings,

FIGURE 1 is a side elevation view of an electric circuit interrupter incorporating the invention;

FIGURE 2 is a plan view of an arc extinguishing portion of the circuit interrupter of FIGURE 1; and

FIGURE 3 is a perspective view of the arc extinguishing 3,i7i,3 Patented Mar. 2, 1965 ice assembly of the invention apart from the insulating hous ing of the circuit interrupter.

In the drawings, the invention is shown as. incorporated in an electric circuit interrupter including a generally rectangular insulating housing having a base 10' and a cover 11. The circuit breaker illustratedv is a three. pole circuit breaker, that is, it is adapted to control electric current in three separate electrical paths, each of saidv paths comprising a pole portion of the circuit breaker. For the purposes of the present invention, the current path through the central one of said poles only will be described. It will be understood however that the invention is equally applicable to single, two. and three pole devices, the construction at the other poles being substantially identical. v

An. incoming line terminal member 12. is provided, sup.- ported on thev base 10 by an insert 13, connected to a first elongated. terminal member or strapli by suitable means such as. by a screw 15. The. terminal member 14 carries a. stationary contact 16 at its inner end, which is. adapted to be contacted by a movable contact 17 carried, by a second elongated-conductor in theform of Contact arm 18. The contact arm 13 is pivotally supported by suitable means'such aSby pivot pin 1% on a main contact arm 20. The, contact arm 29 is attachedv to a Contact cross-arm 21 by suitable. insulating means, not shown, which serves to gang together all the corresponding contact arms of the poles of the circuit breaker. The contact arm 18 is connected by a suitable flexible connector 22 to a conductor 25, which in turn is conn cted to an input terminal 24 of a current responsive assembly or trip unit 25. The trip unit 25 has an outgoing or. load terminal strap 26 which is connected, together with a load terminal 27, to an insert Ziiby suitable means, such. as by a screw 219.

All of the contact arms 18 are adapted. to be moved simultaneously between open and closed circuit positions by suitable operating mechanism, includingv an operating link 36 and a releasable member 31, releasably engaged by a latch portion 25A of the trip unit 25; The operating mechanism is adapted to be, operated manually by means of a manually engageable handle member 32 project-ing through an, aperture in, the top wall of the cover 11. The rip unit 25 contain current responsive means for releasably retaining the member 31 in latched condition as shown. Upon the occurrence of predetermined current conditions, the latched member 31 is released, causing automatic opening of the contacts. The releasable member 31 adapted to be re-engaged with the trip unit 25 fol lowing tripping, by movement of the manually operable handle 32 to its 0 position, indicated in dotted lines.

In accordance with the invention, are cooling and extinguishing means is provided comprising a pair of spaced insulating side plates 33 serving to support a plurality of stacked metallic arc plates 34. The side plates 33 terminate a short distance from the corresponding end wall portion 35 of the insulating casing base lib, leaving a vertical channel 36 therebetween. A generally channelshaped lining member 37 of insulating material is received within the channel 36 and protects the Wall 35 from the effects of hot arc gases.

A vent opening 38 is provided in the end Wall portion of the cover 11, and a metallic woven screen member 39 is placed in the opening 38.

When the contacts 16 and 17 separate on the occurrence of high short circuit currents, the arc is drawn forcibly into the plates 34, toward the venting passage 36. For the purpose of assuring that the hot gases are directed mainly upwardly and outwardly through the vent opening 39, and not permitted to blow back into the main mechanism chamber, a deflector plate 40 is provided of insulating material, supported at an angle between the side walls 33, adjacent the vent opening 33, at the top of the passage 3 36. Also, the passage 36 is closed off at the botto thereof by means of a specially formed are chute plate 34A, which extends endwise beyond the ends of the other are chute plates 34 and abuts against the insulating liner 3'7. Further, in accordance with the invention, the bottom plate 34A is made of a thickness substantially double that of the other are chute plates. This provides extra heat absorbing action at this critical point.

As shown particularly in FIG. 3, an arc runner 34B is supported on the terminal strap 14 adjacent the contact 16. A piece of insulation 34C overlies the terminal strap adjacent the are runner 34B. It will be observed that the bottom are chute plate 34A is electrically isolated, and serves to shield the adjacent portions of the conductor strap 14 from direct impingement by the are.

In operation, upon the occurrence of high short circuit current conditions, the latch member 25A is released by the trip unit 25, releasing the releasable member 31 and permitting the operating mechanism to move the movable contacts 17 toward open position at high speed. This draws a power are between the contacts 16 and 17, which is moved by magnetic action into the arc chute plates 34 and toward the vent passage 36. The extended bottom are chute plate 34A prevents these gases from reentering the main circuit breaker mechanism chamber below the assembly are chute plates 34. The deflector plate 40, likewise prevents re-entry of the ionized gases toward the mechanism chamber at the top of the passage 36, and directs them outwardly through the vent opening 38 through the metallic screen 39. The extra mass of the bottom are chute plate 34A further provides heat absorbing ability and shields the conductive strap 14 from the effects of the are.

While the invention has been described in connection with one particular embodiment, it will be readily apparent that many modifications thereof may readily be made, and it is therefore intended by the appended claims to cover all such modifications as fall within the true spirit and scope of the inventionl What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit interrupter comprising:

(a) an insulating enclosure,

(12) at least one pair of relatively movable contacts in said casing,

(c) a pair of spaced insulating side plates adjacent said contacts,

(d) a plurality of vertically stacked spaced metallic are plates supported between said side plates and each having a generally V-shaped notch cut therein from one edge thereof, at least one of said relatively movable contacts being movable along a path within said aligned V-shaped notches,

(e) said side plates and said are plates being spaced away from a corresponding end wall of said insulating enclosure to provide a vertically extending arc vent passage, having a top end and a bottom end,

(f) a vent opening in said insulating casing adjacent said top end of said arc passage,

(g) an arc deflector plate extending between said side plates adjacent said vent opening for preventing reentry of arc gases into said enclosure and for directing said arc gases out of said vent opening,

(h) the bottom-most one of said are plates being extended to close off said bottom end of said are passage to prevent re-entry of said are gases into said enclosure and to assist in directing said are gases out said vent opening,

(i) said bottom-most plate having a thickness substantially twice that of the other of said are chute plates whereby to provide a substantial heat absorbing body and (1') a t rminal strap extending from one of said relatively movable contacts outwardly of said insulating enclosure across the bottom end of said are vent passage,

(k) said bottom-most plate also serving to shield said terminal strap from said are gasses.

2. An electric circuit interrupter as set forth in claim 1, said interrupter also including a generally channel-shaped insulating lining member within said are vent passage between the ends of said are chute plates and the adjacent end wall of said insulating enclosure to shield said end wall of said insulating enclosure from said are gases.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCI-IAEFER, Examiner. 

1. AN ELECTRIC CIRCUIT INTERRUPTER COMPRISING: (A) AN INSULATING ENCLOSURE, (B) AT LEAST ONE PAIR OF RELATIVELY MOVABLE CONTACTS IN SAID CASING, (C) A PAIR OF SPACED INSULATING SIDE PLATES ADJACENT SAID CONTACTS, (D) A PLURALITY OF VERTICALLY STACKED SPACED METALLIC ARC PLATES SUPPORTED BETWEEN SAID SIDE PLATES AND EACH HAVING A GENERALLY V-SHAPED NOTCH CUT THEREIN FROM ONE EDGE THEREOF, AT LEAST ONE OF SAID RELATIVELY MOVABLE CONTACTS BEING MOVABLE ALONG A PATH WITHIN SAID ALIVNED V-SHAPED NOTCHES, (E) SAID SIDE PLATES AND SAID ARC PLATES BEING SPACED AWAY FROM A CORRESPONDING END WALL OF SAID INSULATING ENCLOSURE TO PROVIDE A VERTICALLY EXTENDING ARC VENT PASSAGE, HAVING A TOP END AND A BOTTOM END, (F) A VENT OPENING IN SAID INSULATING CASING ADJACENT SAID TOP END OF SAID ARC PASSAGE, (G) AN ARC DEFLECTOR PLATE EXTENDING BETWEEN SAID SIDE PLATES ADJACENT SAID VENT OPENING FOR PREVENTING REENTRY OF ARC GASES INTO SAID ENCLOSURE AND FOR DIRECTING SAID ARC GASES OUT OF SAID VENT OPENING, (H) THE BOTTOM-MOST ONE OF SAID ARC PLATES BEING EXTENDED TO CLOSE OFF SAID BOTTOM END OF SAID ARC PASSAGE TO PREVENT RE-ENTRY OF SAID ARC GASES INTO SAID ENCLOSURE AND TO ASSIST IN DIRECTING SAID ARC GASES OUT SAID VENT OPENING, (I) SAID BOTTOM-MOST PLATE HAVING A THICKNESS SUBSTANTIALLY TWICE THAT OF THE OTHER OF SAID ARC CHUTE PLATES WHEREBY TO PROVIDE A SUBSTANTIAL HEAT ABSORBING BODY AND (J) A TERMINAL STRAP EXTENDING FROM ONE OF SAID RELATIVELY MOVABLE CONTACTS OUTWARDLY OF SAID INSULATING ENCLOSURE ACROSS THE BOTTOM END OF SAID ARC VENT PASSAGE, (K) SAID BOTTOM-MOST PLATE ALSO SERVING TO SHIELD SAID TERMINAL STRAP FROM SAID ARC GASSES. 